| Topic: |
Science > Physics |
| User: |
"Black Wind" |
| Date: |
24 Apr 2006 06:12:57 AM |
| Object: |
Speed of Particles Falling on Black Hole |
1.. What is approx. speed of particles falling into a black hole( at
Event Horizon)
2.. How much time does a big star takes to empty into a black hole
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| User: "PD" |
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| Title: Re: Speed of Particles Falling on Black Hole |
24 Apr 2006 07:53:23 AM |
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Black Wind wrote:
1.. What is approx. speed of particles falling into a black hole( at
Event Horizon)
Could be anything from 0 to just under the speed of light. There is no
common speed.
2.. How much time does a big star takes to empty into a black hole
That depends on how far away the star is, and how fast it is moving
relative to the BH. Again, there is no common answer.
PD
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| User: "Black Wind" |
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| Title: Re: Speed of Particles Falling on Black Hole |
24 Apr 2006 09:18:27 AM |
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That depends on how far away the star is, and how fast it is moving
relative to the BH. Again, there is no common answer.
PD
I was just wondering how long it will take for a star, let us say like
our Sun, close enough to a black hole to begin pulling matter away from
star. Considering the size of a BH just a few ( I think 3-4) kilometers
across it would appear like a gigantic tank full of water emptying into
a tiny drain. A few hundred years perhaps! Is that correct?
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| User: "PD" |
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| Title: Re: Speed of Particles Falling on Black Hole |
24 Apr 2006 12:46:10 PM |
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Black Wind wrote:
That depends on how far away the star is, and how fast it is moving
relative to the BH. Again, there is no common answer.
PD
I was just wondering how long it will take for a star, let us say like
our Sun, close enough to a black hole to begin pulling matter away from
star. Considering the size of a BH just a few ( I think 3-4) kilometers
across it would appear like a gigantic tank full of water emptying into
a tiny drain. A few hundred years perhaps! Is that correct?
I'd say that's a vast underestimate, but I don't know the distribution
of lifetimes of such processes. Try googling "accretion disk"
PD
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| User: "Sam Wormley" |
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| Title: Re: Speed of Particles Falling on Black Hole |
24 Apr 2006 09:43:38 AM |
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Black Wind wrote:
That depends on how far away the star is, and how fast it is moving
relative to the BH. Again, there is no common answer.
PD
I was just wondering how long it will take for a star, let us say like
our Sun, close enough to a black hole to begin pulling matter away from
star. Considering the size of a BH just a few ( I think 3-4) kilometers
across it would appear like a gigantic tank full of water emptying into
a tiny drain. A few hundred years perhaps! Is that correct?
You didn't specify the mass of the black hole, nor its velocity wrt the
sun. What are the orbits of the sun and black hole. Hyperbolic or parabolic
with a quick one-time encounter? Elliptical? What's the eccentricity?
Matter is not transferred unless Roche lobe intersect.
Roche Lobe
http://scienceworld.wolfram.com/physics/RocheLobe.html
Lagrange Points
http://scienceworld.wolfram.com/physics/LagrangePoints.html
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| User: "Sam Wormley" |
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| Title: Re: Speed of Particles Falling on Black Hole |
24 Apr 2006 09:49:54 AM |
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Sam Wormley wrote:
Black Wind wrote:
That depends on how far away the star is, and how fast it is moving
relative to the BH. Again, there is no common answer.
PD
I was just wondering how long it will take for a star, let us say like
our Sun, close enough to a black hole to begin pulling matter away from
star. Considering the size of a BH just a few ( I think 3-4) kilometers
across it would appear like a gigantic tank full of water emptying into
a tiny drain. A few hundred years perhaps! Is that correct?
You didn't specify the mass of the black hole, nor its velocity wrt the
sun. What are the orbits of the sun and black hole. Hyperbolic or parabolic
with a quick one-time encounter? Elliptical? What's the eccentricity?
Matter is not transferred unless Roche lobe intersect.
Roche Lobe
http://scienceworld.wolfram.com/physics/RocheLobe.html
Lagrange Points
http://scienceworld.wolfram.com/physics/LagrangePoints.html
You also need Roche Limit
http://scienceworld.wolfram.com/physics/RocheLimit.html
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